Application of Botox in The Management Of Musculoskeletal Pain

INTRODUCTION– SEROTYPES AND MECHANISM OF ACTION Botulinum Toxin happens to be one of the most potent neurotoxins comprising of a 50 kDa light chain and a 100kDa heavy chain, which are linked by a disulphide bond. 7 serotypes ranging from A to G have been identified.  It exists in seven serotypes, A through G. It has been seen the Botulinum Toxin is responsible for  interference with the expression  of various neuropeptides such as Substance P and calcitonin gene- related protein (CGRP), which are key mediators of neurogenic inflammation.[1] Botulinum toxin A(BoNT/A) injections have been seen to reduce paw edema in formalin treated rat cadavers, lower the tissue glutamate release and obtund spinal cord excitability.[2] In all, it has been recognised that Botulinum is an inhibitor of cytokines, neuropeptides and other inflammatory mediators. Lot of clinical studies support the proposed anti- nociceptive mechanism of action o0f Botulinum Toxin.[3-5]

APPLICATIONS– The neuromuscular blockade brought about by BOTOX has been seen to give good relief of pain and improvement of function in patients suffering with painful and chronic musculoskeletal ailments.

• OSTEOARTHRITIS– BOTOX is being increasingly used in the non invasive management of arthritis of the knee, hip, shoulder and other joints as well. Significant improvement in pain scores and quality of life was seen in  a lot of patients. Moore and colleagues saw marked improvement in patients of knee arthritis, injected with BOTOX.
• PLANTAR FASCITIS– One of the commonest foot and ankle condition encountered in the society, BoNT injections are helpful in resistant cases( failure of physical therapy and steroid injections). Significant improvement of pain and the near absence of side effects has made it popular amongst the Musculoskeletal practitioners today.
• TEMPEROMANDIBULAR JOINT PAIN– Pain over the temperomandibular region  which is secondary to overactivity of the masticatory muscles responds well to intramuscular BOTOX injections. Injections  are usually given via an oral route. Studies have shown that the usual preferred dose is 50 units into the masseter and 25 units injected into the temporalis. Studies have reported upto 80% of patients experiencing lasting  pain relief upto  10-12 months.
• TENNIS ELBOW/ LATERAL EPICONDYLITIS: Probably the most common cause of tennis elbow, studies have reported reduced pain and improvement in daily activities after BoNT-A injection. Care has to be taken to monitor the dosage as reductions in finger movement and grip strength have occurred due to the  motor effects of BoNT-A, although the motor block is only temporary in nature.
• CHRONIC EXERTIONAL COMPARTMENT SYNDROME: A condition resulting in compression symptoms due to increased pressure in an osteofascial muscle compartment,  usually after exercise. Based on limited evidence, BoNT-A injections may be a safe and effective treatment, in some cases avoiding the need for surgery.

References

1. Birklein F, Schmelz M: Neuropeptides, neurogenic inflammation and complex regional pain syndrome (CRPS). Neurosci Lett. 2008;437(3):199–202 10.1016/j.neulet.2008.03.081 [PubMed] [CrossRef] [Google Scholar]
2. Cui M, Khanijou S, Rubino J, et al. : Subcutaneous administration of botulinum toxin A reduces formalin-induced pain. Pain. 2004;107(1–2):125–33 10.1016/j.pain.2003.10.008 [PubMed] [CrossRef] [Google Scholar]
3. Krämer HH, Angerer C, Erbguth F, et al. : Botulinum Toxin A reduces neurogenic flare but has almost no effect on pain and hyperalgesia in human skin. J Neurol. 2003;250(2):188–93 10.1007/s00415-003-0971-x [PubMed] [CrossRef] [Google Scholar]
4. Yuan RY, Sheu JJ, Yu JM, et al. : Botulinum toxin for diabetic neuropathic pain: a randomized double-blind crossover trial. Neurology. 2009;72(17):1473–8 10.1212/01.wnl.0000345968.05959.cf [PubMed] [CrossRef] [Google Scholar]
5. Ranoux D, Attal N, Morain F, et al. : Botulinum toxin type A induces direct analgesic effects in chronic neuropathic pain. Ann Neurol. 2008;64(3):274–83 10.1002/ana.21427 [PubMed] [CrossRef] [Google Scholar]